Fabrication of broadband antireflection structures on glass substrates by Reactive Ion Etching for application on homogenizers in CPV systems

Efrain E Tamayo R1,2, Kentaroh Watanabe1, Masakazu Sugiyama1,2, Takuya Hoshii1,2, Yasushi Shoji2, Yoshitaka Okada1,2, Kenjiro Miyano1 1Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Meguro-ku, Japan /2School of Engineering, The University of Tokyo, Bunkyo-ku, Japan

Concentrated Photovoltaic (CPV) systems are a potential candidate to achieve low cost solar energy [1].  In these systems the efficiency of the solar cell increases with concentration and the amount of semiconductor material required is lower.  CPV systems use Fresnel lenses to focus the light into homogenizers, which uniformizes the flux distribution incident to the subjacent solar cell and does other optical corrections.  A disadvantage of these optical elements is that they create three optical interfaces that reflect the incident light and together account for about 12% of losses.  To achieve higher efficiency in CPV systems, these losses need to be addressed.  In this paper we report on the fabrication of antireflection structures on glass substrates by Reactive Ion Etching (RIE) that could be applied to the curved surface of the latest generation homogenizers [2].